《深入浅出MySQL》之SQL基础
SQL是Structure Query language（结构化查询语言）的缩写，它是使用关系模型的数据库应用语言。在众多开源数据库中，MySQL正是其中最杰出的代表，MySQL是由三个瑞典人于20世纪90年代开发的一个关系型数据库。并用了创始人之一Michael Widenius女儿的名字My命名，这就是MySQL的由来，本次博客使用的是开源数据库MySQL，版本5.7.19,下面就开始吧！
SQL分类
1.数据定义语句（Data Definition Language,DDL）：主要是用来定义数据库、表、列等对象；
2.数据操作语句（Data Manipulation language,DML）：用来添加、更新、删除和查询数据库记录，并检查数据完整性；
3.数据控制语句（Data Control language,DCL）：定义了数据库、表、用户的访问权限和安全级别等；
DDL语句
1.创建数据库
语法：create database dbname;
举例：
mysql> create database test;
Query OK, 1 row affected (0.01 sec)
查看当前系统中有哪些数据库：
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
5 rows in set (0.00 sec)
选择要操作的数据库：
mysql> use test
Database changed
查看数据库中所创建的表：
mysql> show tables;
Empty set (0.00 sec)
mysql> use mysql
Database changed
mysql> show tables;
+---------------------------+
| Tables_in_mysql |
+---------------------------+
| columns_priv |
| db |
| dept |
| emp |
| engine_cost |
| event |
| func |
| general_log |
| gtid_executed |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| innodb_index_stats |
| innodb_table_stats |
| ndb_binlog_index |
| plugin |
| proc |
| procs_priv |
| proxies_priv |
| server_cost |
| servers |
| slave_master_info |
| slave_relay_log_info |
| slave_worker_info |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
+---------------------------+
33 rows in set (0.00 sec)
2.删除数据库
语法:drop database dbname;
举例：
mysql> drop database test;
Query OK, 0 rows affected (0.00 sec)
注意：删除数据库后，数据库下面的所有的的表就被清空了，再删除之前记得备份有用的数据。
3.创建表
create table tablename(
column_name_1 column_type_1 constraints,
column_name_2 column_type_2 constraints,
...
column_name_2 column_type_2 constraints,
);
举例：
mysql> create table emp(name varchar(10),hiredate date,sal decimal(10,2),dept int(2));
Query OK, 0 rows affected (0.04 sec)
查看表：
语法：desc tablename
举例：
mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(10) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dept | int(2) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
4 rows in set (0.01 sec)
查看表的详细信息：
mysql> show create table emp \G;
*************************** 1. row ***************************
Table: emp
Create Table: CREATE TABLE `emp` (
`name` varchar(10) DEFAULT NULL,
`hiredate` date DEFAULT NULL,
`sal` decimal(10,2) DEFAULT NULL,
`dept` int(2) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec) ERROR:
No query specified
4.删除表
语法：drop table tablename
举例：
mysql> drop table emp;
Query OK, 0 rows affected (0.01 sec)
5.修改表
（1）修改表类型：
语法：alter table tablename modify column_name column_type_new
举例：
mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(10) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dep | int(2) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
4 rows in set (0.00 sec) mysql> alter table emp modify name varchar(20);
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> alter table emp modify name varchar(20);
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dep | int(2) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
（2）增加表字段：
语法:alter table tablename add column column_name column_type;
举例：
mysql> alter table emp add column age int(3);
Query OK, 0 rows affected (0.06 sec)
Records: 0 Duplicates: 0 Warnings: 0 mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dep | int(2) | YES | | NULL | |
| age | int(3) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
5 rows in set (0.00 sec)
（3）删除表字段：
alter table tablename drop column column_name
举例：
mysql> alter table emp drop column age;
Query OK, 0 rows affected (0.17 sec)
Records: 0 Duplicates: 0 Warnings: 0 mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dep | int(2) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
（4）字段改名
语法：alter table tablename change old_column_name new_column_name column_type
举例：
mysql> alter table emp change dep dept int(3);
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dept | int(3) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
change和midify都可以修改表，change可以修改列的名称和重新定义列的类型，modify却不能修改列的名称。
（5）修改字段排列的顺序
语法：alter table tablename change/add/modify column_name column_type first/after column_name
举例：
mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dept | int(3) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
4 rows in set (0.00 sec) mysql>
mysql>
mysql> alter table emp add column age int(2) after name;
Query OK, 0 rows affected (0.06 sec)
Records: 0 Duplicates: 0 Warnings: 0 mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| age | int(2) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dept | int(3) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
5 rows in set (0.00 sec)
（6）修改表名
语法：alter table tablename rename new_tablename
举例：
mysql> alter table emp rename emp1;
Query OK, 0 rows affected (0.01 sec)
mysql> desc emp1;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| age | int(2) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dept | int(3) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
5 rows in set (0.00 sec)
DML语句
DML是对数据库中的表的操作，是开发人员最长使用的。
1.插入记录
语法：insert into tablename(column_name1,column_name2,...column_namen) values(value1,value2,...valuen);
举例：
mysql> desc emp;
+----------+---------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+---------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| age | int(2) | YES | | NULL | |
| hiredate | date | YES | | NULL | |
| sal | decimal(10,2) | YES | | NULL | |
| dept | int(3) | YES | | NULL | |
+----------+---------------+------+-----+---------+-------+
5 rows in set (0.00 sec)
mysql> insert into emp(name,age,hiredate,sal,dept) values('frank',22,'2017-09-15','',1);
Query OK, 1 row affected (0.00 sec)
mysql> insert into emp values('rose',21,'2017-09-15','',1); #也可以不指定字段名称，但是后面的顺序必须和字段保持一致
Query OK, 1 row affected (0.00 sec)
mysql> insert into emp values('jeff',23,'2017-09-15','',2),('mei',21,'2017-09-15','',3); #可以同时插入多条记录
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> insert into emp(name,sal) values('lisa',''); #没写的字段默认为NULL
Query OK, 1 row affected (0.00 sec)
查看表emp：
mysql> select * from emp;
+-------+------+------------+----------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+----------+------+
| frank | 22 | 2017-09-15 | 10000.00 | 1 |
| rose | 21 | 2017-09-15 | 10000.00 | 1 |
| jeff | 23 | 2017-09-15 | 10000.00 | 2 |
| mei | 21 | 2017-09-15 | 8000.00 | 3 |
| lisa | NULL | NULL | 1000.00 | NULL |
+-------+------+------------+----------+------+
5 rows in set (0.00 sec)
2.更新记录
（1）更新单个表
语法：update tablename set column_name1=value1,column_name2=value2,...column_namen=valuen [where condition]
举例：
mysql> select * from emp;
+-------+------+------------+----------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+----------+------+
| frank | 22 | 2017-09-15 | 10000.00 | 1 |
| rose | 21 | 2017-09-15 | 10000.00 | 1 |
| jeff | 23 | 2017-09-15 | 10000.00 | 2 |
| mei | 21 | 2017-09-15 | 8000.00 | 3 |
+-------+------+------------+----------+------+
4 rows in set (0.00 sec)
mysql> update emp set sal='' where name='rose';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from emp;
+-------+------+------------+----------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+----------+------+
| frank | 22 | 2017-09-15 | 10000.00 | 1 |
| rose | 21 | 2017-09-15 | 4000.00 | 1 |
| jeff | 23 | 2017-09-15 | 10000.00 | 2 |
| mei | 21 | 2017-09-15 | 8000.00 | 3 |
+-------+------+------------+----------+------+
4 rows in set (0.00 sec)
在MySQL中update可以同时更新多个表中数据：
语法：update tablename1 alias1 ,table2 alias2 set update_condition where condition
举例：
mysql> select * from emp;
+-------+------+------------+----------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+----------+------+
| frank | 22 | 2017-09-15 | 10000.00 | 1 |
| rose | 21 | 2017-09-15 | 4000.00 | 1 |
| jeff | 23 | 2017-09-15 | 10000.00 | 2 |
| mei | 21 | 2017-09-15 | 8000.00 | 3 |
+-------+------+------------+----------+------+
4 rows in set (0.00 sec) mysql> select * from dep;
+-------+---------+
| depno | depname |
+-------+---------+
| 1 | tecg |
| 2 | sale |
| 3 | fin |
| 4 | IT |
+-------+---------+
4 rows in set (0.00 sec) mysql> update emp a,dep b set a.sal=a.sal*b.depno where a.dept=b.depno;
Query OK, 2 rows affected (0.00 sec)
Rows matched: 4 Changed: 2 Warnings: 0 mysql> select * from emp;
+-------+------+------------+----------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+----------+------+
| frank | 22 | 2017-09-15 | 10000.00 | 1 |
| rose | 21 | 2017-09-15 | 4000.00 | 1 |
| jeff | 23 | 2017-09-15 | 20000.00 | 2 |
| mei | 21 | 2017-09-15 | 24000.00 | 3 |
+-------+------+------------+----------+------+
4 rows in set (0.00 sec)
3.删除记录
语法：delete from tablename [where condition];
举例：
mysql> select * from emp;
+-------+------+------------+----------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+----------+------+
| frank | 22 | 2017-09-15 | 10000.00 | 1 |
| rose | 21 | 2017-09-15 | 4000.00 | 1 |
| jeff | 23 | 2017-09-15 | 20000.00 | 2 |
| mei | 21 | 2017-09-15 | 24000.00 | 3 |
+-------+------+------------+----------+------+
4 rows in set (0.00 sec) mysql> delete from emp where name='mei';
Query OK, 1 row affected (0.00 sec) mysql> select * from emp;
+-------+------+------------+----------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+----------+------+
| frank | 22 | 2017-09-15 | 10000.00 | 1 |
| rose | 21 | 2017-09-15 | 4000.00 | 1 |
| jeff | 23 | 2017-09-15 | 20000.00 | 2 |
+-------+------+------------+----------+------+
3 rows in set (0.00 sec)
也可以同时删除多个表的记录：
语法:delete alias1,alias2 from tablename1 alias1,tablename2 alias2 where condition;
举例：
mysql> select * from emp;
+-------+------+------------+----------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+----------+------+
| frank | 22 | 2017-09-15 | 10000.00 | 1 |
| rose | 21 | 2017-09-15 | 4000.00 | 1 |
| jeff | 23 | 2017-09-15 | 20000.00 | 2 |
+-------+------+------------+----------+------+
3 rows in set (0.00 sec)
mysql> select * from dep;
+-------+---------+
| depno | depname |
+-------+---------+
| 1 | tecg |
| 2 | sale |
| 3 | fin |
| 4 | IT |
+-------+---------+
4 rows in set (0.00 sec) mysql> delete a,b from emp a,dep b where a.dept=b.depno;
Query OK, 5 rows affected (0.00 sec) mysql> select * from dep;
+-------+---------+
| depno | depname |
+-------+---------+
| 3 | fin |
| 4 | IT |
+-------+---------+
2 rows in set (0.00 sec) mysql> select * from emp;
Empty set (0.00 sec)
4.查询记录
语法:select * from tablename [where condition]; #*表示把所有的记录都拿出来
举例：
mysql> select * from emp;
+-------+------+------------+---------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+---------+------+
| rose | 22 | 2017-09-12 | 1000.00 | 1 |
| jeff | 23 | 2017-09-12 | 2000.00 | 1 |
| frank | 23 | 2017-09-15 | 2000.00 | 2 |
| bob | 24 | 2017-02-15 | 3000.00 | 3 |
+-------+------+------------+---------+------+
4 rows in set (0.00 sec)
（1）查询指定字段：
mysql> select name,age from emp;
+-------+------+
| name | age |
+-------+------+
| rose | 22 |
| jeff | 23 |
| frank | 23 |
| bob | 24 |
+-------+------+
4 rows in set (0.00 sec)
（2）查询不重复的记录：
添加关键字distinct
mysql> select age from emp;
+------+
| age |
+------+
| 22 |
| 23 |
| 23 |
| 24 |
+------+
4 rows in set (0.00 sec) mysql> select distinct age from emp;
+------+
| age |
+------+
| 22 |
| 23 |
| 24 |
+------+
3 rows in set (0.00 sec)
（2）条件查询
mysql> select name,age from emp where age > 23;
+------+------+
| name | age |
+------+------+
| bob | 24 |
+------+------+
1 row in set (0.00 sec)
（4）排序和限制
desc和asc是排序的关键字，desc表示按照字段继续降序排序，asc则表示按照字段升序排序，默认是升序。order by后面可以跟着对个排序字段。
举例：
mysql> select * from emp order by sal; #默认是升序
+-------+------+------------+---------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+---------+------+
| rose | 22 | 2017-09-12 | 1000.00 | 1 |
| jeff | 23 | 2017-09-12 | 2000.00 | 1 |
| frank | 23 | 2017-09-15 | 2000.00 | 2 |
| bob | 24 | 2017-02-15 | 3000.00 | 3 |
+-------+------+------------+---------+------+
4 rows in set (0.00 sec)
mysql> select * from emp order by sal desc; #使用降序
+-------+------+------------+---------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+---------+------+
| bob | 24 | 2017-02-15 | 3000.00 | 3 |
| jeff | 23 | 2017-09-12 | 2000.00 | 1 |
| frank | 23 | 2017-09-15 | 2000.00 | 2 |
| rose | 22 | 2017-09-12 | 1000.00 | 1 |
+-------+------+------------+---------+------+
4 rows in set (0.00 sec)
如果对排序之后只想显示其中的一部分，可以使用limit关键字，order by和llimit经常一起配合使用来进行记录的分页显示。
mysql> select * from emp order by sal desc limit 2;
+------+------+------------+---------+------+
| name | age | hiredate | sal | dept |
+------+------+------------+---------+------+
| bob | 24 | 2017-02-15 | 3000.00 | 3 |
| jeff | 23 | 2017-09-12 | 2000.00 | 1 |
+------+------+------------+---------+------+
2 rows in set (0.00 sec)
（5）聚合
语法：select [column_name1,colun_name2,...] fun_name from tablename [where condition] [group by column_name1,colun_name2,...[with rollup] [having where condition]]
fun_name：表示聚合操作，也就是聚合函数，常用的有sum(求和),count(计数),max(最大值),min(最小值)
group by：要进行分类聚合的字段
with rollup：表明是否对分类聚合后的结果进行再汇总
having：表示对分类后的结果再进行过滤
举例：
mysql> select count(1) from emp;
+----------+
| count(1) |
+----------+
| 4 |
+----------+
1 row in set (0.00 sec) mysql> select dept,count(1) from emp group by dept;
+------+----------+
| dept | count(1) |
+------+----------+
| 1 | 2 |
| 2 | 1 |
| 3 | 1 |
+------+----------+
3 rows in set (0.00 sec)
mysql> select dept,count(1) from emp group by dept having count(1) > 1;
+------+----------+
| dept | count(1) |
+------+----------+
| 1 | 2 |
+------+----------+
1 row in set (0.00 sec)
mysql> select dept,count(1) from emp group by dept with rollup;
+------+----------+
| dept | count(1) |
+------+----------+
| 1 | 2 |
| 2 | 1 |
| 3 | 1 |
| NULL | 4 |
+------+----------+
4 rows in set (0.00 sec)
mysql> select sum(sal),max(sal),min(sal) from emp;
+----------+----------+----------+
| sum(sal) | max(sal) | min(sal) |
+----------+----------+----------+
| 8000.00 | 3000.00 | 1000.00 |
+----------+----------+----------+
1 row in set (0.00 sec)
（6）表连接
内连接：选出两张表中互相匹配的记录
mysql> select name,dept from emp,dep where emp.dept=dep.depno;
+------+------+
| name | dept |
+------+------+
| bob | 3 |
+------+------+
1 row in set (0.00 sec)
外连接：左连接和右连接,外连接会选出其他不匹配的记录。
左连接：
mysql> select name,depname from emp left join dep on emp.dept=dep.depno;
+-------+---------+
| name | depname |
+-------+---------+
| bob | fin |
| rose | NULL |
| jeff | NULL |
| frank | NULL |
+-------+---------+
4 rows in set (0.00 sec)
右连接：
mysql> select name,depname from dep right join emp on emp.dept=dep.depno;
+-------+---------+
| name | depname |
+-------+---------+
| bob | fin |
| rose | NULL |
| jeff | NULL |
| frank | NULL |
+-------+---------+
4 rows in set (0.00 sec)
（7）子查询
子查询的关键字：in、not in、=、!=、exists、not exists；
mysql> select * from emp where dept in (select depno from dep);
+------+------+------------+---------+------+
| name | age | hiredate | sal | dept |
+------+------+------------+---------+------+
| bob | 24 | 2017-02-15 | 3000.00 | 3 |
+------+------+------------+---------+------+
1 row in set (0.00 sec)
（8）联合
关键字:union和union all，union去会对结果去重。
举例：
mysql> select * from emp;
+-------+------+------------+---------+------+
| name | age | hiredate | sal | dept |
+-------+------+------------+---------+------+
| rose | 22 | 2017-09-12 | 1000.00 | 1 |
| jeff | 23 | 2017-09-12 | 2000.00 | 1 |
| frank | 23 | 2017-09-15 | 2000.00 | 2 |
| bob | 24 | 2017-02-15 | 3000.00 | 3 |
+-------+------+------------+---------+------+
4 rows in set (0.00 sec) mysql> select * from dep;
+-------+---------+
| depno | depname |
+-------+---------+
| 3 | fin |
| 4 | IT |
+-------+---------+
2 rows in set (0.00 sec) mysql> select dept from emp
-> union all
-> select depno from dep;
+------+
| dept |
+------+
| 1 |
| 1 |
| 2 |
| 3 |
| 3 |
| 4 |
+------+
6 rows in set (0.00 sec)
mysql> select dept from emp
-> union
-> select depno from dep;
+------+
| dept |
+------+
| 1 |
| 2 |
| 3 |
| 4 |
+------+
4 rows in set (0.00 sec)
DCL语句
DCL语句一般是数据库管理员用来对对象进行授权使用的，一般开发人员是很少用的，这里先做简单的介绍，后面的博客会更新相关内容：
创建用户：
mysql> create user 'frank'@'%' identified by '';
Query OK, 0 rows affected (0.00 sec)
授权：
mysql> grant all privileges on test.* to 'frank'@'%' identified by '';
Query OK, 0 rows affected, 1 warning (0.00 sec)
退出root登录frank：
C:\Windows\system32>mysql -ufrank -p
Enter password: ***
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.19 MySQL Community Server (GPL) Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| test |
+--------------------+
2 rows in set (0.00 sec) mysql>
帮助使用
查看所有可供查询的分类：
mysql> ? contents
You asked for help about help category: "Contents"
For more information, type 'help <item>', where <item> is one of the following
categories:
Account Management
Administration
Compound Statements
Data Definition
Data Manipulation
Data Types
Functions
Functions and Modifiers for Use with GROUP BY
Geographic Features
Help Metadata
Language Structure
Plugins
Procedures
Storage Engines
Table Maintenance
Transactions
User-Defined Functions
Utility
mysql> ? data types #进一步查看
You asked for help about help category: "Data Types"
For more information, type 'help <item>', where <item> is one of the following
topics:
AUTO_INCREMENT
BIGINT
BINARY
BIT
BLOB
BLOB DATA TYPE
BOOLEAN
CHAR
CHAR BYTE
DATE
DATETIME
DEC
DECIMAL
DOUBLE
DOUBLE PRECISION
ENUM
FLOAT
INT
INTEGER
LONGBLOB
LONGTEXT
MEDIUMBLOB
MEDIUMINT
MEDIUMTEXT
SET DATA TYPE
SMALLINT
TEXT
TIME
TIMESTAMP
TINYBLOB
TINYINT
TINYTEXT
VARBINARY
VARCHAR
YEAR DATA TYPE
快速查找：
举例：查找create table怎么使用？
mysql> ? create table
Name: 'CREATE TABLE'
Description:
Syntax:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
(create_definition,...)
[table_options]
[partition_options] CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
[(create_definition,...)]
[table_options]
[partition_options]
[IGNORE | REPLACE]
[AS] query_expression CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
{ LIKE old_tbl_name | (LIKE old_tbl_name) }
......(略)
参考书籍 《深入浅出MySQL》 写的很不错，推荐！
《深入浅出MySQL》之SQL基础的更多相关文章
- （2.16）Mysql之SQL基础——函数
(2.16)Mysql之SQL基础——函数 关键词:mysql函数,mysql自定义函数,mysql聚合函数,mysql字符串函数,mysql数值函数 1.自定义函数 -- (1)一般形式 creat ...
- （2.15）Mysql之SQL基础——开发设计最佳规范
(2.15)Mysql之SQL基础——开发设计最佳规范 关键字:mysql三大范式,mysql sql开发规范 分析: show profile.mysqllsla.mysqldrmpslow.exp ...
- （2.14）Mysql之SQL基础——游标
(2.14)Mysql之SQL基础——游标 关键词:Mysql游标 -- (1)定义游标 declare cur_name cursor for select * from table_name wh ...
- （2.13）Mysql之SQL基础——触发器
(2.13)Mysql之SQL基础——触发器 关键词:Mysql触发器 1.一般形式 -- 0.查看触发器[1]SHOW TRIGGERS;[2]SELECT * FROM `information_ ...
- （2.11）Mysql之SQL基础——存储过程与变量
(2.11)Mysql之SQL基础——存储过程 关键字:mysql存储过程 查看存储过程: []SELECT * FROM information_schema.ROUTINES WHERE ROUT ...
- （2.10）Mysql之SQL基础——约束及主键重复处理
(2.10)Mysql之SQL基础——约束及主键重复处理 关键词:mysql约束,批量插入数据主键冲突 [1]查看索引: show index from table_name; [2]查看有约束的列: ...
- （2.9）Mysql之SQL基础——索引的查看与删除
(2.9)Mysql之SQL基础——索引的查看与删除 关键词:mysql索引查看,mysql索引删除 1.索引查询(以下包括主键,唯一,普通,复合,全文,但不包括外键) (1)按库查询 select ...
- （2.8）Mysql之SQL基础——索引的分类与使用
(2.8)Mysql之SQL基础——索引的分类与使用 关键字:mysql索引,mysql增加索引,mysql修改索引,mysql删除索引 按逻辑分类: 1.主键索引(聚集索引)(也是唯一索引,不允许有 ...
- （2.7）Mysql之SQL基础——表的操作与查看
(2.7)Mysql之SQL基础——表的操作与查看 搜索关键字:mysql表操作,comment注释操作,mysql临时表 0.临时表 create temporary table 1.创建表(在in ...
- （2.6）Mysql之SQL基础——存储引擎的查看与修改
(2.6)Mysql之SQL基础——存储引擎的查看与修改 可以使用 show engines; 查看数据库支持的所有的存储引擎: 目录: 1.数据库级别存储引擎 1.1查看现在默认的存储引擎 1.2 ...
随机推荐
- MATLAB的神经网络工具箱介绍
一.使用matlab2010b以后的版本会有完整的神经网络工具箱,使用nnstart可以调出toolbox,然后选择需要的功能,导入数据,选择训练参数和每层神经元个数,最后训练会输出网络与结果. 二. ...
- 勤快的love枫[ZJOI2007]
题目描述 小绝恋love 枫是一个出纳,经常需要做一些统计报表的工作.今天是绝恋love 枫的生日,小绝恋love 枫希望可以帮爸爸分担一些工作,作为他的生日礼物之一.经过仔细观察,小绝恋love 枫 ...
- 从零开始编写动态库文件Makefile，C++版
这篇文章前,假设你已经看过<跟我一起写Makefile(一)>,陈皓写的那个. 对现有的一个C++动态库文件和调用程序,分别编写Makefile文件,从零开始,花了四天时间才搞清楚一半,生 ...
- hexdump命令的使用
hexdump命令是Linux下的打印16进制的利器,它可以按我们指定的格式输出16进制,特别有用,配合eeprom来用简直是绝配. 今天我们来介绍一个hexdump命令的使用: 首先我们准备一个测试 ...
- 神经网络中的BP神经网络和贝叶斯
1 贝叶斯网络在地学中的应用 1 1.1基本原理及发展过程 1 1.2 具体的研究与应用 4 2 BP神经网络在地学中的应用 6 2.1BP神经网络简介 6 2.2基本原理 7 2.3 在地学中的具体 ...
- vcruntime140.dll丢失解决
之前安装好apache2.4后,打开突然报这样的错误,所以百度一下,发现了问题所在,原因是系统需要安装一个插件,才能正常运行apache2.4 Microsoft Visual C++ 2005 Re ...
- pythonchallenge
# _*_ coding:utf-8 _*_ translated = '' message = 'g fmnc wms bgblr rpylqjyrc gr zw fylb. rfyrq ufyr ...
- 基于react全家桶+antd-design+webpack2+node+express+mongodb开发的前后台博客系统
很久没更新博客,最近也有点忙,然后业余时间搞了一个比较完整基于react全家桶+antd-design+webpack2+node+express+mongodb开发的前后台博客系统的流程系统,希望对 ...
- Shell curl 和 wget 使用代理IP
Linux Shell 提供两个非常实用的命令来爬取网页,它们分别是 curl 和 wget curl 和 wget 使用代理 curl 支持 http.https.socks4.socks5 wge ...
- 关于flask线程安全的简单研究
flask是python web开发比较主流的框架之一,也是我在工作中使用的主要开发框架.一直对其是如何保证线程安全的问题比较好奇,所以简单的探究了一番,由于只是简单查看了源码,并未深入细致研究,因此 ...